The present invention relates to a sheet post-processing apparatus including a unit for binding sheets or a bundle of sheets, and to an image forming system including the sheet post-processing apparatus and a copier, a printer, a facsimile machine or a combination thereof.
In the conventional sheet post-processing apparatuses having stitching units for stitching sheet bundles or any other stitching units, there are a type that the sheet bundle is moved to a position of a stapler before stitching the sheet bundle at a desired position, and a type that the stapler is moved to the sheet bundle before stitching the sheet bundle at a desired position.
The conventional sheet post-processing apparatuses having the stitching units for stitching the sheet bundle or other stitching units have a problem that a head or an anvil tends to rub the sheet bundle if a gap between the head and the anvil is not enough. This is due to a relative movement of the sheet bundle and the stapler irrespective of whether the gap between the head and the anvil is enough or not. Stitching may be made in a situation that the sheet bundle is deformed in the posture with the stapler moved. In the worst case, jamming happens.
In view of the foregoing problems, it is an object of the present invention to provide a sheet post-processing apparatus having a stitching unit capable of properly stitching a sheet bundle, and an image forming system containing an image forming apparatus having the sheet post-processing apparatus built therein.
Further objects and advantages of the invention will be apparent from the following description of the invention.
In order to attain the above objects, the present invention is composed of a head part to drive a staple into a sheet bundle; an anvil part to receive and to bend the staple driven by the head part; a holding station for placing the sheet bundle thereupon between the head part and the anvil part; first moving means for moving at least one of the head part and the anvil part toward the other to nip the sheet bundle placed on the holding station between the head part and the anvil part; second moving means for relatively moving the head part, the anvil part and the sheet bundle along surfaces of the sheet bundle placed on the holding station, both of which faces the head part and the anvil part; gap detecting means for detecting a gap between the head part and the anvil part; and inoperating means for making the second moving means inoperable according to the detection result of the gap detecting means.
In accordance with another aspect of the present invention, the sheet post-processing apparatus includes a head part for driving staples on sheet bundles discharged sequentially from an image forming apparatus and stacked; an anvil part for receiving and bending the staples driven from the head part; a holding station for placing the sheet bundle thereupon between the head part and the anvil part; first moving means for moving at least one of the head part and the anvil part toward the other to nip the sheet bundle placed on the holding station in between the head part and the anvil part; second moving means for relatively moving the head part and the anvil part, and the sheet bundle along surfaces of the sheet bundle placed on the holding station, both of which face the head part and the anvil part; gap detecting means for detecting a gap between the head part and the anvil part; inoperating means for making the second moving means inoperable according to a detection result of the gap detecting means; sheet bundle feeding means for feeding the sheet bundles stitched by the head part and the anvil part; and a stacking station for stacking the sheet bundle fed by the sheet bundle feeding means.
In accordance with a further aspect of the present invention, the image forming apparatus includes an image forming station for forming an image on a sheet; a head part for driving staples on sheet bundles discharged sequentially from an image forming station and stacked; an anvil part for receiving and bending staples driven from the head part; a holding station for placing the sheet bundle thereupon between the head part and the anvil part; first moving means for moving at least one of the head part and the anvil part toward the other to nip the sheet bundle placed on the holding station in between the head part and the anvil part; second moving means for relatively moving the head part, the anvil part and the sheet bundle along surfaces of the sheet bundle placed on the holding station, both of which face the head part and the anvil part; gap detecting means for detecting a gap between the head part and the anvil part; inoperating means for making the second moving means inoperable according to a detection result of the gap detecting means; sheet bundle feeding means for feeding the sheet bundle stitched by the head part and the anvil part; and a stacking station for stacking the sheet bundle fed by the sheet bundle feeding means.